For what it's worth, I built something very similar to this and it ran for 7 years until Google shut it down for violating the terms of service. Here's a blog post I wrote with specifics, I case it also applies to your service. https://critter.blog/2020/08/04/a-farewell-to-toogles/
I think the difference here is that Piped is using a custom backend server (piped-backend) which scrapes youtube html to obtain the video content/metadata (a-la invidious), while your app was using the youtube API. Google is allowed to shut your app down, but AFAIK can't police who can and can't consume their publicly available HTML.